Fluidic phase monitor



, `1970l l G. A.- THIRY FLUIDIC I VHASE MONITOR Feb. 10

2 Sheets-Sheet 1 Filed Nov. 24. r 196'? Feb. l0, 1970 G. A. THIRYFLUIDIC PHASE MON ITOR 2 sheds-sheet 2 Filed Nov. 24. 1967 INVENTOR.

@Y f il United States Patent O 3,494,371 FLUIDIC PHASE MGNITOR Geza A.Thiry, Lakewood, Ohio, assignor to Houdaille Industries, Inc., acorporation of Michigan Filed Nov. 24, 1967, Ser. No. 685,627 Int. Cl.FlSc 3/00; 606m 1/12; G06d 1/04 U.S. Cl. 137-815 8 Claims ABSTRACT 0FTHE DISCLOSURE A fluidic switch applies bias to a fluidic diode tocontain the charge of a iluidic capacitor, or of elements havingcapacitance. At a preset charge value, the bias of the diode is removeduntil discharge occurs. After substantial discharge, bias isautomatically reestablished.

Such charge-value-responsive removal of bias may correspond to atiming-out operation indicating malfunction of a monitored elementintended to have a higher operating frequency than the characteristicfrequency of the charge-discharge cycle of a capacitor which iscontinuously fed from a pressure source. The recycling of the monitoredelement provides an alternative bias control that must repeatedly causeremoval of the bias prior to attainment of the pre-set charge value inorder to avoid a malfunction indication.

This invention relates to means for discharging a iluidic capacitor, orelements having iluidic capacitance, and to iluidic means for applyingand removing diode bias and to a fluidic timer that may utilize thecharacteristic period of a charge-discharge cycle of a fluidiccapacitor, or of elements having capacitance.

According to one application of the invention, a fluidic capacitor, orelements having capacitance, may be continuously charged from a pressuresource and periodically both discharged and reset for charge at acharacteristically regular frequency that may be adjusted by varying therate of charge. The system can be employed so that such resettingcorresponds to a timing-out operation indicating malfunction of amonitored element intended to have a higher frequency of operation thanthe characteristic charge-discharge frequency to which the capacitor isadjusted and that operates as an alternative resetting means.

An object of the invention is to provide, in a fluidic system, capacitormeans and a uidic diode biased to contain the charge of the capacitormeans together with means responsive to charging of the capacitor meansto a pre-set value for removing the bias of the diode until thecapacitor means discharges substantially, and for thereuponreestablishing the bias'.

Another object of the invention is the provision of a iluidic phasemonitor for making a time comparison between the frequency of a standardcharge-discharge cycle and the frequency of operation of a monitoredelement.

It will be understood that, as used herein, capacitor means includeseither a capacitor, as such, or parts of fluidic system having theproperty of iluidic capacitance.

The foregoing and other objects and changes of the invention will bebetter understood from the following description which is given by wayof example and not by way of limitation.

In the drawings, FIGURE 1 is a schematic representation of a fluidicsystem embodying the invention, and FIGURE 2 is a view of a systemsimilar to FIGURE l but including certain refinements.

DESCRIPTION OF SYSTEM OF FIGURE 1 In FIGURE 1 is shown a fluidic controlsystem which may have the well-known form of an integrated iluidic3,494,371 Patented Feb. 10, 1970 circuit formed in laminar material, ormay have the form of physically separate fiuidic elements joined bysmall tubes. Assuming that the system is integrated, the external ttingsof such an integrated system can be at the locations marked x. Leadingfrom a pressure source (not shown) is a pressure supply line 7 whichleads into the main internal pressure header 8. This, through suitablepressure reducing restrictions R1, R2, R3, leads to various branch linesas illustrated.

The system shown may be employed to monitor the frequency of operationor cycling of a cyclic type lubricant distributor or any otherperiodically operating device indicated schematically at 9. Themonitored device may have a rotating shaft or any other element adoptedto periodically close otf a vent or port 13; for example, theillustrated cyclic type distributor has a reciprocating element 10operated by the back and forth movement of a valve stem to close thevent or port 13 at the end of a 'short external line, although it willbe understood that any other element adapted to intermittently close or0bstruct a vent may be utilized, as, for example, a projecting ear ortab on a rotating shaft or the like.

In the system shown in FIGURE l, a capacitor 11 in the form of a simpletank is provided connected to the header 8 via an adjustable needlevalve 12 which constitutes adjustable throttling means. A counter 42 maybe provided of a known type adapted to tally the number of times thatthe capacitor is pressurized and dumped to above and below certainpressure valves (say respectively 6 p.s.i. and 1 p.s.i.). Also providedis a iluidic diode 18 which is adapted to allow How upwardly as viewedin FIGURE 1, but not in the reverse direction. This diode may be ailapper valve or any other simple mechanical valve adapted to operate toallow flow in one direction if the pressure is higher on the input sidethan on the output side in such direction of ilow, but adapted to stopflow in the opposite direction.

In the illustrated system, uidic elements include a nor gate 17, astandard or non-biased flip-Hop switch 15, and a one-shot multivibrator20. The nor switch or gate 17 is of standard design and provided withcontrol inlets or ports 23, 25 and 31 and with conventional vents (notshown). In a well-known manner the control inlets or ports 23 and 25 areadapted, upon the reception of supplied pressure signals, to shift asignal received through the incoming power line 48 from a power outletor power output port 19 to a power outlet or power output port 24 andare pressure signal control inlets. The outlet passage leading to eachpower output port is vented in the conventional `manner (see for examplepage 42 of Fluidic Systems Design Guide, First Edition, 1966, FluidonicsDivision, Imperial-Eastman Corporation, 6300 W. Howard St., Chicago,lll. 60648). The switch 17 is also adapted, upon the reception of avacuum signal at control inlet or port 31, as upon closing off a vent orport 32, to similarly shift power output from power outlet or port 19`to power outlet port 24, and the control inlet 31 will be understood tobe a vacuum signal control inlet. The switch 17 is a nor switch in thesense that power output at port 19 indicates that there is a controlpressure signal in neither port 23 nor port 25. Switches of the abovetype and general description are well known.

The vent or port 32 may simply be the Open end of a branch line 47. Thisvent or port 32 may be closed olf in response to the building ofpressure in aline 46 leading from the capacitor 11 by interposition ofan expansiblechamber motor means 14, which comprises bellows 45 adaptedto close off the port 32 upon a suicient pressure rise (say 8 p.s.i.)within the bellows 45, and to open the port 32 when pressure within theline 46 and the bellows 45 drops below such value.

Although the vacuum-imposing control switch 14 involves mechanicalmovement incidental to expansion and contraction of the bellows 45, itinvolves no sliding rr1o tion. Since mechanical movement is involved,the period of operation and the inertial lag of the device may besubstantial as compared to pure fluidic gate, but are adequateconsidering the required frequency of operation of the device.

The ip-ilop switch is of a well-known type in which control ports 28 and33 are adapated to flip the power input via line 34 to one or the otherof the output ports 35 and 36 depending upon what control signals areapplied to the control ports 28 and 33. A pressure pulse at 28 or avacuum pulse at 33 ilips output to port 36, while a pressure pulse at 33or a vacuum pulse at 33 flips output to port 35. Thus, closing bleed orvent 37 may impose a vacuum pulse to act as a reset control, and suchclosing will flip the switch 15 to the output port 36 to activate thenormal operation indicator 38. The normal operation indicator 38 and themalfunction or flow indicator 39 may comprise Visiwink controls of aknown commercial type comprising colored discs adopted to be moved byline signal pressure into position where they become visible through aviewing glass..

The one-shot multivibrator is of a known type adapted to momentarilyshift power output from port 40 to port 22 upon reception of atriggering signal or pulse via control port 41 and to thereuponautomatically reestablish power output at port 40. In general, the risetime of the control pulse at the port 41 should be of shorter durationthan the normal duration of the temporary output of port 22. Thisimplies a positive abrupt closing of port 13. Where the closing of theport is likely to be of longer duration an additional nor switch 21(FIGURE 2) may be employed, in a manner to be later described inconnection with the description of the ernbodiment of FIGURE 2. Also,when it is desired to provide lthe flip-flop switch 15 in the form of abiased ipop, it is desirable to provide another nor switch 16 (FIGURE2), in a manner to be later described in connection with the descriptionof the embodiment of FIG- URE 2.

However, for the time being, it will be assumed that these refinementsare not used, in order that the invention may be more readily describedand understood.

OPERATION OF SYSTEM IN FIGURE l The capacitor 11 lls at a constant ratefrom the pressure supply source 7 via the needle valve 12. This valvemay be adjusted to vary the rate of lling of the capacitor I11, and thusto vary, within limits, the period of operation of the system.

The capacitor 11 is dumped periodically, this dumping being caused byperiodic reclosing of the port 13 in a manner to be described below. Ifthis reclosing of the port 13 does not occur promptly enough, pressurebuilds to the point (say 7 p.s.i) where vacuum-imposing control switch14 closes thereby, via line 30, switching llip-flop switch 15 to port 35and causing a trouble signal to appear at 39. Also the signal via theoutput port 35 may go to a spool valve of any known type, for example aMiller valve (not shown), that comprises a large power amplifier forautomatic shut-down or start up of 'a controlled system such as acentralized lubricating distributor system.

Periodic reclosing of the port 13 causes periodic dumping of thecapacitor in the following manner. Prior to such reclosing, the norswitch 17 normally maintains a bias (say 8 p.s.i.) at the diode 18 viathe power outlet port 19 of the nor switch. That is, during such time asoutlet or port 19 is the operative power outlet or port, incoming powervia line 48 is applied through nor power outlet or port v19 againstdiode 18. Characteristically there is a substantial pressure drop acrossthe nor Switch 17 between the power input lead 48 and the power outputport 19 (through-switch flow being exhausted via the vent associatedwith port 19), so that say 25 pounds input pressure becomes say 8 pounds0n the immediately -upstream side of diode 18, thus maintaining the justmentioned bias.

With this bias established, capacitor 11 continues charging up towardthe bias value of say 8 p.s.i. However, reclosing of the port 13 iiresthe one-shot multivibrator 20 by applying a pressure signal of short orlong duration at control inlet or port 41 causing a temporary outputsignal via alternate power outlet or port 22 of the multivibrator 20.This signal, via the control port 23 of nor switch 17, shifts powerincoming via line 32 to the or power outlet or port 24. This, in turn,establishes a feedback to the control inlet or port 25 via the loop 26,so that output to power outlet 24 is maintained after cessation of anincoming signal at control port 23. However, because of bleeding of thefeedback loop 26 at vent 27, the flow incoming via line 48 is insuicientin itself to maintain the feedback signal without supplementation byldischarge of the capacitor as described immediately be ow.

With shifting of output to port 24, there occurs a background venting ordumping of the capacitor through the internal Vents of switch 17,through vent 27, and in part through the loop 26, because, with biasremoved from the diode 18, the capacitor 11 discharges across thisdiode, into port 19, back around the internal power passaging of the norswitch 17, out of port 24, and out vent 27 and around the feedback loop26. Vent 27 bleeds the feedback loop 26 which, in this described stateof the system, is carrying a waning signal as discharge of the capacitor11 nears completion. When the signal drops sutlciently, the nor switch17 switches from the power outlet 24 to the power outlet 19, completingthe dumping phase. Pressure then 4starts to climb again in capacitor 11,starting another filling cycle.

As previously stated, if reclosing of the port 13 does not occurpromptly enough, the capacitor is not dumped soon enough to avoidpressure buildup in the vacuumimposing control switch 14, which, when itcloses, switches flip-flop switch 15, causing a trouble signal, all asabove described. Closing of the vacuum-imposing switch 14 also dumps thecapacitor 11 by removing bias of the diode 18 because such elementvacuum switches the nor switch 17 via the line 29 as well as vacuumswitching via the line 30 as above described. The capacitor continues torecharge and be dumped by closing of element 14 until such time as thetrouble is remedied, i.e., until the cycle time of the monitored systemagain becomes brief enough so that the capacitor is dumped by closing of13 rather than by closing of 32.

After trouble has been indicated and eliminated, and it is desired torecommence normal operation of the monitor, the port 37 may be closedmomentarily to reset power output in flip-flop switch 15 to port 36.Since flip-flop switch 15 is not biased in the FIGURE l system it isalso necessary to close port 37 momentarily after each start-up of thesystem in order to be sure that flip-flop switch 15 is feeding poweroutput port 36 rather than power output port 35 at start-up. Otherwise afalse trouble signal will occur.

DESCRIPTION AND OPERATION OF SYSTEM OF FIGURE 2 FIGURE 2 is similar toFIGURE 1, and like elements have like reference numbers. However, thenor switches 16 and 21 have been added and the switch 15 has beenconverted to a biased Hip-flop switch, the favored outlet beingindicated by a -l-. For proper relationship of the operating parts,indicators 38 and 39 have been reversed in position in FIGURE 2 fromtheir position in FIGURE l, and of course the connections to acontrolled spool valve would have been correspondingly reversed. Port 37has been replaced by a spring-loaded push-button or plunger control 43of a well-known type adapted to be momentarily lmanually depressed byfinger pressure to generate a momentary pressure pulse for resetting.

Since flip-flop switch I5 is biased, it automatically feeds power toport 35 upon system start-up. The push-button 43 is not strictlynecessary, but without it the system must be shut down and restartedafter each malfunction indication in order to reset the flip-flop forno-rmal operation. With push-button 43, resetting can be accomplishedwithout shutting down the system by providing momentary pressure pulsegenerated by push-button 43 and applied at control port 33.

Aberrations in the operation of one-shot multivibrator 20 may occur ifthe rise time of the triggering pulse at control port 41 is of longerduration than the characteristic period of the momentary output at port22. To avoid this possibility, nor switch 21 is provided. An incomingpressure pulse caused by rapid or slow closing of orifice 13 will resultin an abrupt pressure rise at control port 41 of the multivibrator 2f),thus assuring proper operation of the multivibrator.

Without limitation, and by way of example only, typical circuit valuesmay be given. The incoming line pressure may be 25 p.s.i. The dropthrough resistor R1 may be to 1/2 p.s.i. The drop through resistors R2may be to l2 p.s.i. The drop through resistor R3 may be to 6 p.s.i. Withconventional commercially available circuit elements such as flip-flop15, nor switches 16, 17, 21, and multivibrator 2li), and conventionalinterconnecting lines, typical cycle of charge and discharge of thecapacitor may be varied from .2 second to 400 seconds, depending uponthe adjustment of the needle valve 12. For the longer end of this timerange, say from about l0 seconds to about 400 seconds, the petcock 44may remain open to utilize the full capacity of the capacitor 11. Forthe shorter or briefer end of this time range, say from about .2 secondto about 15 seconds, the petcock 44 may be closed to utilize theinherent capacitance of the lines interconnecting the diode 18 with theelements 12, 14, and 42.

Elements may be changed, eliminated and added without departing from theinvention.

What is claimed is:

1. In a fluidic system, capacitor means, a fluidic diode biased byoutlet back-pressure to contain the charge of said capacitor means,means responsive to charging of said capacitor means to a pre-set valuefor removing the outlet back-pressure bias of said diode until saidcapacitor means discharges substantially and for thereuponreestablishing said bias.

2. Apparatus as in claim 1 including charging means and adjustablethrottling means for throttling said charging means to vary thecharacteristic period of the chargedischarge cycle.

3. Apparatus as in clai-m 1, said means responsive to charging forremoving, then reestablishing, bias, including a fluidic nor switchhaving a vented vacuum signal control inlet and also including anexpansible-chamber motor means adapted to close off said venting at agiven pressure in said capacitor means.

4. In a fluidic system, capacitor means, means for continuously feedingsaid capacitor means from `a pressure source, a uidic diode capable ofbeing biased to contain the charge of said capacitor means, fluidicswitch means having a first power outlet means via which said bias isapplied and second power outlet means via which power is directed toremove said bias, first and second control inlet means each of which isadapted to switch power from said first to said second power outletmeans upon reception of its own signal, and indicating means responsiveto a signal received by the first of said control inlet means but not toa signal received by the second of said control inlet means, wherebyoperation of said indicating means occurs when bias is removed solelyvia the first of said control inlet means and not when bias is removedsolely via the second of said control inlet means.

5. In apparatus as in claim 4, means for generating signals forreception by the first of said control inlet means in response tocharging of said capacitor 'means to a preset value, whereby when biasis removed via the said second control inlet means to allow discharge ofsaid capacitor means, a signal for reception at the said first controlinlet means cannot then occur.

6. In a fluidic system, a nor switch, capacitor means connected to apressure source via the nor power outlet of the nor switch, a liuidicdiode between the nor power outlet and the capacitor means and blockingflow into the capacitor means from the nor power outlet, a vacuum signalcontrol inlet in the nor switch for shifting power from the nor poweroutlet to the or power outlet upon reception of a vacuum signal as byblocking of a vent port connected to the vacuum signal control inlet, atleast one pressure signal control inlet, and feedback loop means fromthe or power outlet to the pressure signal control inlet.

7. Apparatus as in claim 6, said feedback loop means including Imeansfor attenuating the power signal from said pressure source to such anextent that it alone is ineffective to impose a control signal withoutreinforcement from power transmitted by discharge of said capacitormeans across said diode, into sand nor power outlet, back around the norswitch interior to said or power outlet, and thence around said loop.

8. In a iiuidic system, a iiuidic switch having first and second poweroutlets, capacitor means connected to a pressure source via said firstpower outlet, a fluidic diode between said first power outlet and thecapacitor means and blocking flow into the capacitor means from saidfirst power outlet, control inlet means for shifting power from Saidfirst to said second power outlet upon reception of a control signal,and feedback loop means from said second power outlet to a control inletof said control inlet means.

References Cited UNITED STATES PATENTS 2,248,363 7/ 1941 Kuenhold13.7-206 3,144,309 8/1964 Sparrow 137-815 X 3,392,741 7/1968 Shinn137-815 M. CARY NELSON, Primary Examiner WILLIAM R. CLINE, AssistantExaminer U.S. C1. X.R. 23S-201

